Transfer of Virus by a Direct Leaf-to-leaf Method

Abstract

IN evaluating sources of tobacco mosaic virus (TMV) resistance in tomato1 to a fruit disorder2, large numbers of mature plants grown in the field and greenhouse were indexed just prior to inoculation with TMV. This was necessary because the presence of related or unrelated viruses has been shown to interfere with TMV multiplication3,4. Since the usual method of indexing by juice inoculation to indicator hosts required considerable time spent in washing mortars and pestles between transfers, a less time-consuming method of inoculation seemed desirable. The leaf-to-leaf method described here is a modification of Yarwood's leaf-disk method5 in which the freshly cut edges of leaf disks are used in the inoculation of labile viruses.